Before you try to remove the rust give the surface a good clean to make sure you don’t have any organic residue on it. This would mask any chemical removal of the rust. Simple Green, Scotchbrite pads and lots of elbow grease
Rust removers can be dangerous to use as they sometimes contain hydroflouric acid in dilute amounts. This is the secret sauce that dissolves rust without attacking the base metal. HF is very dangerous to work with.
In theory phosphoric acid converts iron rust to a water soluable salt. In practice it’s not that effective so “Naval Jelly” type products drop the pH and put some corrosion inhibitors to counter act the lower pH to help the Phosphoric acid work better.
What ever you use to go after the rust make sure you do a good job of rinsing the surface and nooks and crannies with water and then dry the surface carefully.
Regards,
Mike Jolley